The following abbreviations are herewith defined, at least some of which are referred to within the following description of the prior art and the present disclosure.    ACK Acknowledgement    AP Access Point    ARQ Automatic Repeat Request    ASIC Application-Specific Integrated Circuit    BS Base Station    BSC Base Station Controller    BTS Base Transceiver Station    CDMA2000 Code Division Multiple Access    CQI Channel Quality Indicator    D2D Device-to-Device    DAS Distributed Antenna System    DL Downlink    EPROM Erasable Programmable Read Only Memory    EEPROM Electrically Erasable Programmable Read-Only Memory    FDD Frequency Division Duplex    GERAN GSM EDGE Radio Access Network    GSM Global System for Mobile Communications    HARQ Hybrid Automatic Repeat Request    HS-DPCCH High Speed Dedicated Physical Common Control Channel    HSDPA High Speed Downlink Packet Access    HSPA High Speed Packet Access    HS-SCCH High Speed Shared Control Channel    HS-PDSCH High Speed Physical Data Shared Channel    LLE Laptop Embedded equipment    LME Laptop Mounted Equipment    LTE Long Term Evolution    M2M Machine-to-Machine    MIMO Multiple-Input and Multiple Output    MSR Multi-Standard Radio    NAK Non-Acknowledgement    NTBP Number of Transport Blocks Preferred    PCI Precoding Control Index    P-CPICH Primary Common Pilot Channel    PDCCH Physical Downlink Control Channel    PDSCH Physical Downlink Shared Channel    RAB Radio Access Bearer    RAM Random Access Memory    RAT Radio Access Technology    RNC Radio Network Node    RI Rank Information    ROM Read Only Memory    RRC Radio Resource Control    RRH Remote Radio Head    RRU Remote Radio Unit    RoT Rise Over Thermal    SIR Signal-to-Interference Ratio    TDD Time Division Duplex    TI Transaction Identifier    TTI Transmit Time Interval    UE User Equipment    USB Universal Serial Bus    UTRA Universal Terrestrial Radio Access    WLAN Wireless Local Area Network
The Channel Quality Indicator (CQI) is the key indicator for HSDPA DL channel quality and its frequent reporting by the UE to the Node B is essential to maintain a good DL efficiency. The CQI is signaled from the UE to the Node B on one or several uplink HS-DPCCH physical channels, together with other channel state information, depending on the configured downlink transmission mode of the UE. A brief overview of the CQI reporting required by the HSDPA standard is provided next with respect to FIG. 1 (PRIOR ART).
Referring to FIG. 1 (PRIOR ART), there is a signal diagram illustrating the exchange of messages between a RNC 102, a Node B 104, and a UE 106 to establish a data call setup which requires CQI reporting per the HSDPA standard. At step 1, the RNC 102 communicates a reporting period 108 to the UE by RRC signaling either through RRC radio bearer configuration or RRC re-configuration. The RNC 102 sets the reporting period 108 for the UE 106 from a set of values which are provided in 3GPP TS 25.331 V11.11.0 dated Sep. 23, 2014 (the contents of which are incorporated by reference herein). Typically, the minimum CQI reporting period is one TI (2msec). Once the RRC setup is complete, then the Node B 104 at step 2 transmits known symbols 110 (pilots 110) on the Primary Common Pilot Channel (P-CPICH) to the UE 106. The UE 106 receives the known symbols 110 (pilots 110) and estimates the quality of the P-CPICH and computes a CQI 112, a precoding channel indicator 114 (PCI 114) (if applicable), and rank information 116 (RI 116) (if applicable). At step 3, the UE 106 transmits the CQI 112, PCI 114 (if applicable), and RI 116 (if applicable) along with a hybrid ARQ ACK/NAK 118 (HARQ-ACK 118) in a feedback message 120 to the Node-B 104 using the dedicated physical control channel (HS-DPCCH). The structure of the HS-DPCCH's feedback message 120 can take various forms depending on the specific configuration of the UE 106. Three exemplary HS-DPCCH's feedback messages 120a, 120b, and 120c are discussed in detail next with respect to FIGS. 2-4 (PRIOR ART).
Referring to FIG. 2 (PRIOR ART), there is a diagram illustrating the form of one exemplary HS-DPCCH's feedback message 120a for a single carrier when the UE 106 is configured in non-MIMO mode. As shown, the HS-DPCCH's feedback message 120a comprises the following information: HARQ-ACK 1181, CQI 1121, HARQ-ACK 1182, and CQI 1122. The feedback message 120a is well known to one skilled in the art of wireless telecommunications.
Referring to FIG. 3 (PRIOR ART), there is a diagram illustrating the form of another exemplary HS-DPCCH's feedback message 120b when the UE 106 is configured in MIMO mode with two transmit antennas. As shown, the HS-DPCCH's feedback message 120b comprises the following information: HARQ-ACK 1181, CQI 1121, PCI 1141, HARQ-ACK 1182, CQI 1122, PCI 1142, HARQ-ACK 1183, CQI 1123, PCI 1143. Each CQI 1121, 1122, and 1123 is computed as follows:
  CQI  =      {                                                      15              ×                              CQI                1                                      +                          CQI              2                        +            31                                                                                                when                  ⁢                                                                          ⁢                  2                  ⁢                                                                          ⁢                  transport                  ⁢                                                                          ⁢                  blocks                  ⁢                                                                          ⁢                  are                                                                                                      preferred                  ⁢                                                                          ⁢                  by                  ⁢                                                                          ⁢                  the                  ⁢                                                                          ⁢                  UE                                                                                                      CQI            S                                                                                                when                  ⁢                                                                          ⁢                  1                  ⁢                                                                          ⁢                  transport                  ⁢                                                                          ⁢                  block                  ⁢                                                                          ⁢                  is                                                                                                      preferred                  ⁢                                                                          ⁢                  by                  ⁢                                                                          ⁢                  the                  ⁢                                                                          ⁢                  UE                                                                        where CQI is the channel quality per individual layer also defined as transmission rank, which is defined as a MIMO branch with a distinct modulation and transport block size and a HARQ-process identifier.
It can be observed from FIG. 3 (PRIOR ART) and the above equation that if the CQI 112 is less than 31, then the RI 116 is 1, otherwise the RI 116 is 2. The PCI 114 is the precoding information bits which are selected from the subset of the codebook corresponding to the RI 116. The feedback message 120b is well known to one skilled in the art of wireless telecommunications.
Referring to FIG. 4 (PRIOR ART), there is a diagram illustrating the form of another exemplary HS-DPCCH's feedback message 120c when the UE 106 is configured in MIMO mode with four transmit antennas. As shown, the HS-DPCCH's feedback message 120c comprises the following information: HARQ-ACK 1181, CQI 1121, RI 1161, PCI 1141, HARQ-ACK 1182, CQI 1122, RI 1162, PCI 1142. Each CQI 1121, and 1122 is computed as follows:
  CQI  =      {                                                      15              ×                              CQI                1                                      +                          CQI              2                                                                                                                                when                    ⁢                                                                                  ⁢                    2                                    ,                                      3                    ⁢                                                                                  ⁢                    or                    ⁢                                                                                  ⁢                    4                    ⁢                                                                                  ⁢                    transport                    ⁢                                                                                  ⁢                    blocks                    ⁢                                                                                  ⁢                    are                                                                                                                        preferred                  ⁢                                                                          ⁢                  by                  ⁢                                                                          ⁢                  the                  ⁢                                                                          ⁢                  UE                                                                                                      CQI            S                                                                                                when                  ⁢                                                                          ⁢                  1                  ⁢                                                                          ⁢                  transport                  ⁢                                                                          ⁢                  block                  ⁢                                                                          ⁢                  is                  ⁢                                                                          ⁢                  preferred                                                                                                      by                  ⁢                                                                          ⁢                  the                  ⁢                                                                          ⁢                  UE                                                                        where CQI is the channel quality per individual layer also defined as transmission rank, which is defined as a MIMO branch with a distinct modulation and transport block size and a HARQ-process identifier.
Thus, when the UE 106 is configured in MIMO mode with four transmit antennas, the UE 106 provides the Node B 104 the following: HARQ ACK information 118, CQI 112 per codeword, the number of transport blocks preferred (NTBP) also called rank information 116 (RI 116), and the precoding control index 114 (PCI 114). The feedback message 120c is well known to one skilled in the art of wireless telecommunications.
Referring again to FIG. 1 (PRIOR ART), the Node-B 104 upon receiving the feedback message 120 will at step 4 schedule and allocate to the UE 106 the required channelization codes, modulation and coding, precoding channel index, and rank information (if applicable). This scheduling information 122 is conveyed to the UE 106 by the High Speed Shared Control Channel (HS-SCCH). Once the UE 106 detects the HS-SCCH and receives the scheduling information 122, then the downlink transmission 124 to the UE 106 starts from the Node B 104 at step 5 through the High Speed Physical Data Shared Channel (HS-PDSCH).
As can be seen from FIG. 1's step 1, it is common practice today to configure the reporting period 108 for the UE 106 to a fixed value selected from a set of values which are provided in 3GPP TS 25.331 V11.11.0 dated Sep. 23, 2014. However, configuring a fixed value for the reporting period 108 to all the UEs 106 is not beneficial because all the UEs 106 will then need to transmit the feedback messages 120 even though the Node B 104 may not be using that channel quality immediately. Further, the transmissions of the feedback messages 120 on the HS-DPCCH from all the UEs 106 contributes to increase the interference level known as the rise over thermal (RoT) in the uplink. This increase in the interference level happens because all UEs 106 in uplink transmit using the same spreading codes and the UEs 106 are separated by non-orthogonal scrambling codes, which results in the uplink HSPA transmissions including the feedback messages 120 needing to share an interference limited resource. Hence, reducing the interference in uplink frequencies is desirable to ensure high SIR levels on the uplink transmission channel and to maintain a stable system operation. In addition, the UE 106 by having the fixed reporting period 108 is not an efficient use of the UE's battery power because the UE needs to compute the channel quality and report this channel state information to the Node B. Moreover, the UE 106 by having the fixed reporting period 108 does not enable the UE 106 to use all the benefits of Adaptive Modulation and Encoding (AMC) such as system capacity because some UEs may not need to make frequent updates of channel state information.